A Study on reactions of palladium anode catalyst in direct formic acid fuel cells

We investigate the cell performance and characteristics of a direct formic acid fuel cell (DFAFC) using palladium (Pd) as a catalyst for anode. Pd is deposited on the electrolyte using the "direct paint" method. From a continuous three time-test of the polarization curve of the DFAFC, it is found that the catalytic activity of Pd and the cell performance of DFAFC steadily degrade as the tests are proceeded. This behavior may be due to the deactivation of Pd by formate (COOH) and hydroxyl (OH) groups, which are electrochemically dissociated from formic acid solution. Estimations of the degradation, followed by reactivation in activity of Pd catalyst and DFAFC cell performance are implemented by linear voltage sweep tests going in both positive and negative directions. When the maximum voltage of 1.0 V versus DHE is applied to the cell while a linear voltage sweep test going in negative directions, the activity of Pd catalyst and the DFAFC cell performance recover by the rehabilitation in activity of the deactivated Pd.